computer and peripherals - peter-lo.com · computer and peripherals ncomputer urefer only to the...
TRANSCRIPT
1
© Peter Lo 2002 1
HardwareHardware
Part 1: Inside the System Unit
© Peter Lo 2002 2
Computer and PeripheralsComputer and Peripherals
n Computer uRefer only to the Central processing unit
(CPU), the circuitry that processes the data, and the computer’s memory.
n PeripheralsuAll additional hardware components grouped
around the CPU and memory
© Peter Lo 2002 3
Computer Hardware OverviewComputer Hardware Overview
© Peter Lo 2002 4
System UnitSystem UnitnIt is a Box-like case
that contains computer’s electronic components nSometimes called
the Chassis
2
© Peter Lo 2002 5
Exposed System UnitExposed System Unit
© Peter Lo 2002 6
How do computers represent data?How do computers represent data?
nMost computers are digitaln Recognize only two discrete states: on or off
1 1 1 1 1
0 0 0 0 0
on
off
© Peter Lo 2002 7
Binary SystemBinary System
n Number system with two unique digits: 0 and 1Binary
Digit (bit)Electronic
ChargeElectronic
State
© Peter Lo 2002 8
What is a byte?What is a byte?
n Eight bits grouped together is a byte8-bit byte for the number 3
8-bit byte for the number 5
8-bit byte for the capital letter T
3
© Peter Lo 2002 9
Three Popular Coding Systems to Three Popular Coding Systems to Represent DataRepresent Data
° ASCII - American Standard Code for Information Interchange
° EBCDIC - Extended Binary Coded Decimal Interchange Code
° Unicode - coding scheme capable of representing all world’s languages
© Peter Lo 2002 10
How is a Character Sent from How is a Character Sent from Keyboard to Computer?Keyboard to Computer?
Step 2: Electronic signal for letter T sent to system unit
Step 3: Signal changed to its ASCII code (01010100) and stored in memory
Step 4: After processing, binary code for letter T is converted to image on output device
Step 1: Press letter T
© Peter Lo 2002 11
Central Processing Unit (CPU) ?Central Processing Unit (CPU) ?
n Interprets and carries out basic instructions that operate a computer
n Also called the Processor
© Peter Lo 2002 12
Components of the CPUComponents of the CPU
CPU
Arithmetic/Logic Unit
(ALU)
Control Unit
4
© Peter Lo 2002 13
Control UnitControl Unit
Control Unit
Control unit repeatsfour basic operations:
° Fetch - obtain program instruction or data item from memory
° Decode - translate instruction into commands
° Execute - carry out command° Store - write result to memory
° Directs and coordinates operations in computer
© Peter Lo 2002 14
Machine Cycle?Machine Cycle?°Four operations of the CPU comprise a machine cycle°Also called instruction cycle
• Execution time (e-time) - time taken to execute and store
e-time
• Instruction time (i-time) - time taken to fetch and decode
i-time
© Peter Lo 2002 15
An example of a machine cycleAn example of a machine cycle
Student enters math problem (100 x 52) into computer’s memory
Result in memory displays on monitor’s screen
100 x 52
© Peter Lo 2002 16
Available CPU PackagesAvailable CPU Packages
dual inline package (DIP)
pin grid array (PGA)
single edge contact (SEC) cartridge
flip chip-PGA(FC-PGA) package
5
© Peter Lo 2002 17
CPUCPU’’s speed Measurings speed Measuring
° According to how many millions of instructions per second (MIPS) it can process
© Peter Lo 2002 18
Two Designs used for the CPUTwo Designs used for the CPU
CISC(complex instruction set
computing)° Supports large number
of instructions° CPU executes complex
instructions more quickly
RISC(reduced instruction
set computing)
° Supports smaller number of instructions
° CPU executes simple instructions more quickly
© Peter Lo 2002 19
Arithmetic/Logic unit (ALU) Arithmetic/Logic unit (ALU)
n CPU component that performs execution part of the machine cycle
Comparison (greater than, equal
to, or less than)
Arithmetic(addition, subtraction,
multiplication, and division)
..and.and.
..not.not...or.or.Logical(AND, OR,
NOT)© Peter Lo 2002 20
PipeliningPipeliningn CPU begins executing second instruction before
completing first instruction. Results in faster processing
Machine Cycle (without pipelining)
Machine Cycle (with pipelining)
Instruction 1
Instruction 2
Instruction 3
Instruction 4
6
© Peter Lo 2002 21
RegisterRegister
Stores location from where
instruction was fetched
Stores instruction while it is
being decoded
Stores data while ALU processes it
Stores results of calculation
° Temporary storage area that holds data and instructions
© Peter Lo 2002 22
System ClockSystem Clock
n Synchronizes all computer operationsn Each tick is clock cycle
MHz - one million ticks of system clock
GHz – one billion ticks of system clock
© Peter Lo 2002 23
MicroprocessorMicroprocessor
n Single processor chip found in personal computers
© Peter Lo 2002 24
How do personal computer How do personal computer processors compare?processors compare?
7
© Peter Lo 2002 25
CoprocessorCoprocessor
One type is a floating-point coprocessor,
also known as a math or numeric
coprocessor
Chip that assists processor in performing
specific tasks
© Peter Lo 2002 26
Parallel ProcessingParallel Processing°Using multiple processors
simultaneously to execute program faster
°Requires special software to divide problem and bring results together
© Peter Lo 2002 27
Memory: The CPUMemory: The CPU’’s Electronic s Electronic ScratchpadScratchpadnMemory is the temporary storage area for
operating system, application programs, and data n It consists of one or more chips on motherboardn Each byte stored in unique address
© Peter Lo 2002 28
How is memory measured?How is memory measured?
nMemory is measured by number of bytes available
8
© Peter Lo 2002 29
Two types of System Unit MemoryTwo types of System Unit Memory
volatile memoryLoses its contents when Loses its contents when the computer's power is the computer's power is
turned offturned off
volatile memoryLoses its contents when
computer's poweris turned off
nonvolatile memory
Does NOT lose its contents when
computer’s power is turned off
© Peter Lo 2002 30
Random Access Memory (RAM)Random Access Memory (RAM)
nMemory chips that can be read from and written to by processornMost RAM is volatilen The more RAM a computer has, the faster it
operates
memory module
© Peter Lo 2002 31
Two Basic Types of RAM chipsTwo Basic Types of RAM chips
n Dynamic RAM (DRAM)uMost common typeuAlso called main memory
n Static RAM (SRAM)u Used for special applications such as cacheu Faster and more reliable than DRAM chips
© Peter Lo 2002 32
CacheCache
n Helps speed computer processes by storing frequently used instructions and data
n Also called Memory Cache, Cache Store , or RAM Cache
n L1 cache built in processorn L2 and L3 cache not built in
processor n L2 advanced transfer cache most
common
9
© Peter Lo 2002 33
ReadRead--Only Memory (ROM)Only Memory (ROM)n Memory chips that contain data, instructions, or
information that is recorded permanently
BIOS(basic input/output system)
Stored on ROM
Sequence of instructions computer follows to load
operating system and other files when you turn on the
computer
ROM is nonvolatile —
Contents not lost when computer is
turned off
Data can only be read;
cannot be modified in
ROM
© Peter Lo 2002 34
Types of ROM Types of ROM
n FirmwareuROM chips manufactured with permanently written
data, instructions, or information
n PROM (Programmable Read-Only Memory)
uBlank ROM on which you can place items permanentlyn EEPROM (Electrically Erasable Programmable Read-Only Memory)
uType of PROM containing microcode programmer can erase
© Peter Lo 2002 35
Flash MemoryFlash Memory
n Nonvolatile memory that can be erased electronically and reprogrammedn Used with handheld computers and digital
cameras, cellular phones, and automobiles
© Peter Lo 2002 36
CMOSCMOS
n CMOS stand for Complementary Metal-Oxide Semiconductor memoryn Stores information about the computer utype of disk drivesukeyboardumonitorucurrent time and date
n Uses battery to retain information when computer is turned off
10
© Peter Lo 2002 37
Memory Access TimeMemory Access Time
n Speed at which processor can access data from memory directly
n Measured in nanoseconds (ns), which is one billionth of a second
n It takes 1/10 of a second to blink your eye; a computer can perform up to 10 million operations in same amount of time
© Peter Lo 2002 38
BUSBUS° Channel that allows devices inside
computer to communicate with each other
° System bus connects processor and RAM
° Bus width determines numberof bits transmitted at one time
° Word size determines numberof bits processor can interpretand execute at a given time
system bus
RAM
processor
© Peter Lo 2002 39
Expansion BusExpansion Busn Allows processor to communicate with peripherals
fastestnext fastestnext fastestslowest
processor
memory
PCI bus expansion slots ISA bus expansion slots © Peter Lo 2002 40
Expansion SlotExpansion Slot
°An opening, or socket, where circuit board is inserted into motherboard
°Expansion card inserted in expansion slot
expansion card
expansion slot
11
© Peter Lo 2002 41
How are expansion cards used?How are expansion cards used?
© Peter Lo 2002 42
Plug and PlayPlug and Play
n Computer automatically can configure cards and other devices as you install them
© Peter Lo 2002 43
PCMCIA cardPCMCIA card
n Credit card-sized device used to add capabilities to notebook computers
n PCMCIA stand for Personal Computer Memory Card International Association
n Uses include modem, additional memory, and storage
© Peter Lo 2002 44
Flash Memory CardFlash Memory Card
n Adds memory to handheld computers, digital music players, cellular telephones, and similar devices
12
© Peter Lo 2002 45
PortPort keyboard
USBUSB
mouse
telephone line in
game port
monitor
svideo out
network
printer (parallel port)
cable TV
speaker
serial port
microphone
telephone line out
FM reception
°Connects external devices to system unit
© Peter Lo 2002 46
Different Types of ConnectorsDifferent Types of Connectors
© Peter Lo 2002 47
Serial PortSerial Portserial transmission of data
DB-9 female connector
byte representation for number 5 (00110101) byte
representation for number 5 (00110101)
DB-9 male connector
byte representation for number 5 (00110101)
°Transmits one bit of data at a time°Used to connect
slow-speed devices, such as mouse, keyboard, modem
© Peter Lo 2002 48
Parallel PortParallel Portbyte representation for number 1byte representation for number 3
byte representation fornumber 5
DB-25 male connector
DB-25 female connector
°Connects devices that can transfer more than one bit at a time, such as a printer
13
© Peter Lo 2002 49
Universal Serial Bus port (USB) Universal Serial Bus port (USB)
n Connector that supports newer peripherals and plug and play
n Other popular ports include 1394, MIDI, SCSI, and IrDA
USB port
1394 port
© Peter Lo 2002 50
BayBayDVD-ROM drive
CD-RW drive
Zip drive
empty drive bay
floppy disk drive
n Open area inside system unit usedto install additional equipment
© Peter Lo 2002 51
Power SupplyPower Supply
n Converts alternating current (AC) to direct current (DC)n Some peripheral devices have AC adapter
© Peter Lo 2002 52
What ports are on a notebook What ports are on a notebook computer?computer?
keyboard/mouse port
IrDA port
serial port
parallel port video port
USB port
14
© Peter Lo 2002 53
How is data transferred from a How is data transferred from a handheld computer?handheld computer?n An IrDA port allows the handheld computer to
communicate wirelessly with other computers or devicesn Handheld computers also can rest in a cradle, so you can
transfer data to your desktop computer
IrDA port
cradle
© Peter Lo 2002 54
HardwareHardware
Part 2: Data Storage
© Peter Lo 2002 55
What is storage?What is storage?
nMedia and devices used to store and retrieve data, instructions, and information
© Peter Lo 2002 56
How does storage differ from How does storage differ from memory?memory?
When you want to work
with a file, you read it
from storage and place it in
memory
When you are finished with the file, you write it from memory into
storage
n Stores items for future use, rather than temporarily
n Storage is nonvolatile, rather than volatile
15
© Peter Lo 2002 57
How does volatility compare?How does volatility compare?
Contents of storage retained when power is off
Contents of storage retained when power is off
Screen display and contents of most RAM (memory) erased when power is off
Screen display and contents of most RAM (memory) erased when power is off
© Peter Lo 2002 58
What is a storage device and a What is a storage device and a storage Medium?storage Medium?
storage medium
Physical material on which a computer
keeps data, instructions, and
information
storage device
Hardware that records and retrieves items to
and from a storage medium
© Peter Lo 2002 59
readingProcess of transferring data,
instructions, and information from a storage medium into
memory
Serves as a sourceof input
writingProcess of
transferring items from memory to a storage medium
Serves as a source of output
Reading and WritingReading and Writing
© Peter Lo 2002 60
What is access time?What is access time?
Memory (RAM)
Compact Disc
Floppy Disk
Tape
Hard Diskcost
less
exp
ensi
ve
mor
e ex
pens
ive
speed
faster
slower
n Amount of time it takes device to locate item on disk
n Defines speed of disk storage device
16
© Peter Lo 2002 61
What is capacity?What is capacity?n Capacity is the
number of bytes (characters) storage medium can hold
Storage Term
Number of bytes
Kilobyte
Megabyte
Gigabyte
Terabyte
Petabyte
KB
MB
TB
GB
PB
1 thousand
1 million
1 billion
1 trillion
1 quadrillion
Abbreviation
© Peter Lo 2002 62
Memory vs. Storage (Summary)Memory vs. Storage (Summary)
LowestVery SlowBackup Tape
LowSlowCD-ROM Disc
MediumMediumHard diskStorage
HighFastRAM
HighestFastestCache MemoryMemory
Cost per MBAccess SpeedDevice
© Peter Lo 2002 63
Floppy DiskFloppy Disk
n Portable, inexpensive storage mediumn Today’s standard disk is 3.5” wide
© Peter Lo 2002 64
What are the parts of a floppy disk?What are the parts of a floppy disk?n Thin, circular,
flexible film enclosed between two liners
shell
shutter
liner
magnetic coating
flexible thin film
metal hub
17
© Peter Lo 2002 65
How are floppy disk drives How are floppy disk drives designated?designated?
Two floppy drives
drive A
drive B
One floppy drive
drive A
© Peter Lo 2002 66
How does a floppy disk drive work?How does a floppy disk drive work?
6: Read/write heads read data from or write data on the floppy disk
Step 65: Motor positions read/write heads over correct location on disk
Step 5
4: Motor causes floppy disk to spin
Step 4
3: If write instruction, circuit board verifies whether disk can be written to
Step 3
2: Signal sent to control movement of read/write heads and disk
Step 2
1: Shutter moves to expose recording surface on disk
Step 1
© Peter Lo 2002 67
Tracks and SectorsTracks and Sectorsn Track is narrow
recording band that forms full circle on disk surface
n Sector can store up to 512 bytes of data
sector18 per track
track80 per
side
80 tracks per side x 18 sectors per track x 2 sides per disk x 512 bytes per sector = 1,474,560 bytes © Peter Lo 2002 68
Format (for Disk)Format (for Disk)n Process of preparing disk for
reading and writing
n Formatting marks bad sectors as unusable
18
© Peter Lo 2002 69
How to take care a floppy?How to take care a floppy?
n Proper care helps maximize disk’s life n Floppy disk can last at least seven years
© Peter Lo 2002 70
What is a writeWhat is a write--protect notch?protect notch?
write-protected
not write-protected
n Small opening with a cover that you slide
n Protects floppy disks from being erased accidentally
notch closed means you
can write on the disk
notch closed means you
can write on the disk
notch open means you cannot write on the disk
notch open means you cannot write on the disk
© Peter Lo 2002 71
HighHigh--capacity Disk Drivecapacity Disk Drive
n Uses disks with capacities of 100 MB and greatern Primarily used to backup files and transfer files
© Peter Lo 2002 72
Hard DiskHard Disk
n High-capacity storagen Consists of several inflexible, circular platters that store
items electronically
n Components enclosed in airtight, sealed case for protection
hard disk installed in system unit
19
© Peter Lo 2002 73
How does a hard disk work?How does a hard disk work?
4: Head actuator positions read/write head arms over correct location on platters to read or write data
Step 4
2: Small motor spins platters
Step 2
3: When software requests disk access, read/write heads determine location of data
Step 3
1: Circuit board controls movement of head activator and small motor
Step 1
© Peter Lo 2002 74
What is a Cylinder?What is a Cylinder?
n Location of a single track through all plattersn Single movement of
read/write head arms can read same track on all platters
trackcylinder
© Peter Lo 2002 75
A head crash!A head crash!
n Occurs when read/write head touches platter surfacen Spinning creates cushion of air that floats read/write head
above platter
hair
read/write head
dustsmoke
platter
gap
clearance between head and platter is approximately two millionths
of an inch
clearance between head and platter is approximately two millionths
of an inch
gap is half the diameter of a dust particle
gap is half the diameter of a dust particle
© Peter Lo 2002 76
Disk CacheDisk Cache
n Portion of memory processor uses to store frequently accessed items
processor
hard disk
disk cache
processor
hard disk
disk cache
first request for data — to disk cache
processor
hard disk
disk cache
second request for data — to hard disk
first request for data — to disk cache
20
© Peter Lo 2002 77
What is a Partition?What is a Partition?n Formatted hard disk
divided into separate areas called partitionsn Each partition
functions as if it were a separate hard disk drive
drive CDesignation for first
partition or for a single partition on hard disk
drive DDesignation for second partition on hard disk
one hard disk divided into
two partitions
© Peter Lo 2002 78
Removable Hard Disk?Removable Hard Disk?
n Disk drive in which a plastic or metal case surrounds the hard disk so you can remove it from the driven Used for backup or to transfer files
© Peter Lo 2002 79
How does RAID work?How does RAID work?
n Disk system that duplicates data, instructions, and information to improve data reliabilityuMirroring has one backup disk for each disk
uStriping stores data across multiple disks
mirroring(RAID Level 1)
striping
© Peter Lo 2002 80
What Windows Utilities Maintain What Windows Utilities Maintain a Hard Disk Drive?a Hard Disk Drive?
System Tools
21
© Peter Lo 2002 81
Internet Hard Drive?Internet Hard Drive?
n Service on Web that provides storage to computer usersn Most offer free storagen Revenues come from advertisers
© Peter Lo 2002 82
Advantages of Internet hard driveAdvantages of Internet hard drive
Allows offsite backups of data
Others can be authorized to access
data from your Internet hard drive
Files can be accessed from any computer or device
with Web access
Large audio, video, and graphics files can be downloaded to an
Internet hard drive instantaneously
© Peter Lo 2002 83
Compact Disc (CD)Compact Disc (CD)
n Storage medium nMost PCs include some type of compact disc driven Available in variety of formats
CD-ROM
CD-R
CD-RW
DVD-ROM
DVD+RW
© Peter Lo 2002 84
How do you use a compact disc?How do you use a compact disc?n CD drives can read
compact discs, including audio discs
Push button to slide out
the tray
Push button to slide out
the tray
Insert disc, label side upInsert disc,
label side up
Push the same button to close
the tray
Push the same button to close
the tray
22
© Peter Lo 2002 85
How does a laser read data on a How does a laser read data on a compact disc?compact disc?
3: Reflected light deflected to light- sensing diode, which sends digital signal of 1. Absence of reflected light read as digital signal of 0.
1: Laser diode shines light beam toward compact disc
2: If light strikes pit, it scatters. If light strikes land, it is reflected back toward laser diode.
Compact disc label
Compact disc label
lens lens
prism prism
laser diode
laser diode
Step 1Compact disc
label
lens lens
prism prism
laser diode
laser diode
Step 2Compact disc
label
lens lens
prism prism
laser diode
laser diode
pit land
Step 3Compact disc
label
lens lens
prism prism
laser diode
laser diode
Light-sensing
diode
Light-sensing
diode
0 1
pit land
© Peter Lo 2002 86
How data stored on a compact disc?How data stored on a compact disc?
n Typically stores items in single trackn Track divided into evenly sized sectors that store items
Compact disc sectors
Single track spirals to edge of disc
© Peter Lo 2002 87
What is a jewel box?What is a jewel box?
n Protective case for compact disc
jewel box
© Peter Lo 2002 88
How should you care for a How should you care for a compact disc?compact disc?
1: Do not expose to excessive heat or sunlight
2: Do not eat, smoke, or drink near a disc
3: Do not stack
4: Do not touch underside
5: Store in jewel box when not in use
6: Hold disc by its edges
23
© Peter Lo 2002 89
What is a CDWhat is a CD--ROM?ROM?
n Compact disc that uses same laser technology as audio CDs for recording music
n Cannot erase or modify contents
n Typical CD-ROM holds about 650 MBn Commonly used to distribute software and games
© Peter Lo 2002 90
CDCD--R (Compact DiscR (Compact Disc--RecordableRecordable))
n Compact disc onto which you can record text, graphics, and audio
n Write on CD-R using CD burner (recorder) or CD-R drive and special software
n CD-R drive can read and write both audio CDs and standard CD-ROMs
n Cannot erase disc’s contents
© Peter Lo 2002 91
CDCD--RW (compact discRW (compact disc--rewritablerewritable))
n Erasable disc you can write on Multiple TimesnMust have a CD-RW disc, CD-RW software,
and CD-RW drive
© Peter Lo 2002 92
How to Create Audio CD?How to Create Audio CD?
Step 5: User listens to song on personal computer or removes CD and listens to song on portable CD player
11
2a 2b
1
2a 2b
3a 3b
1
2a 2b
3a 3b
4
Step 2a: Song stored on audio CD and purchased by user
OR
Step 2b: Song compressed and stored on Internet
Step 3a: User inserts audio CD into CD-ROM drive, plays song, and copies it to hard disk
OR
Step 3b: User downloads song as audio file to hard disk
Step 1: Artist composes song and creates CD
Step 4: User copies file to CD-RW disc
1
2a 2b
3a 3b
4
5
24
© Peter Lo 2002 93
DVDDVD--ROM (Digital Video DiscROM (Digital Video Disc--ROM)ROM)n High capacity compact disc capable of storing
from 4.7 GB to 17 GBnMust have DVD -ROM drive or DVD player to
read DVD-ROMn Primarily used for moviesn Next-generation software will be delivered on
DVD
© Peter Lo 2002 94
How does a DVDHow does a DVD--ROM store data?ROM store data?
n Two layers of pits are used, where lower layer is semitransparentn Laser can read through it to upper layern DVD+RW is a rewritable DVD
© Peter Lo 2002 95
TapeTape
n Magnetically coated ribbon of plastic capable of storing large amounts of data and information at a low cost
n Primarily used for backup
© Peter Lo 2002 96
Sequential Access vs. Direct AccessSequential Access vs. Direct Access
n Sequential AccessuReading and writing data consecutively uMethod used for tape
n Direct AccessuCan locate a particular data item or file
immediately uMethod used for floppy disks, hard disks, and
compact discs uAlso called Random Access
25
© Peter Lo 2002 97
Enterprise Storage SystemEnterprise Storage System
Network Storage Internet backupNetwork StorageNetwork Storage
CD-ROM jukeboxes
Internet backup
tape library
Network Storage
CD-ROM jukeboxes
Internet backup
RAID
Storage area network
servers
tape library
Network storage
CD-ROM jukeboxes
Internet backup
n Strategy that focuses on availability, protection , organization, and backup of storage in a company
© Peter Lo 2002 98
Miniature Mobile Storage MediaMiniature Mobile Storage Media
n Handheld devices use to augment internal storage
CompactFlash
Memory Stick
Microdrive
SmartMedia
40 MB
2 to 256 MB
1 GB
2 to 128 MB
CartridgeDigital cameras, notebook computers
Memory CardDigital cameras, handheld computers, notebook computers, printers, cellular telephones
Memory CardDigital cameras, handheld computers, music players, video cameras
Memory CardDigital cameras, handheld computers, photo printers, cellular telephones
© Peter Lo 2002 99
Smart CardSmart Card
n Stores data on thin microprocessor embedded in credit card
smart card
© Peter Lo 2002 100
Types of smart cardsTypes of smart cardsStore data such as
photographs, music, books, and video clips
n Intelligent smart card contains processor and has input, process, output, and storage capabilities
n Memory card has only storage capabilities
Store a prepaid dollar amount that is updated when the card is
used
Store patient records, vaccination data, and other
healthcare information
Store tracking information such as customer purchases or
employee attendance
26
© Peter Lo 2002 101
Electronic MoneyElectronic Moneyn Means of paying for
goods and services over the Internet
n Also callede-money or digital cash
Bank issues unique digital cash numbers
that represent an amount of money
When you purchase digital cash, the amount
of money is withdrawn from
your bank account
To use the card, swipe it through
a card reader
© Peter Lo 2002 102
Microfilm and MicroficheMicrofilm and Microfichen Store microscopic images of
documents on a roll or a sheet of filmn Images recorded using a computer
output microfilm (COM) recorder
MicroficheUses a small sheet
of film, usually4” x 6”
MicrofilmUses a 100- to 215-
foot roll of film
© Peter Lo 2002 103
Life expectancies of various mediaLife expectancies of various media
© Peter Lo 2002 104
What is a backup?What is a backup?n Duplicate of file, program, or
disk that you can use if original is lost, damaged, or destroyed
data
instructions
information
27
© Peter Lo 2002 105
HardwareHardware
Part 3: Input and Output
© Peter Lo 2002 106
What is input?What is input?
n Data
uUnprocessed facts, figures, and symbols
n InstructionsuProgramsuCommands
uUser responses
DATA Susan works 42 hours at $300/hr
hard disk
COMMANDS
print the
timeca
rd
PROGRAMS
timeca
rd
USER RESPONSES
Yes, the tim
ecard entries
are correc
t
No, the tim
ecard e
ntries ar
e not co
rrect
INSTRUCTIONS
© Peter Lo 2002 107
What is an input device?What is an input device?
n Any hardware component used to enter data, programs, commands, and user responses into a computer
scanners and reading devices
voice inputkeyboard
pointing device
video input
digital camera © Peter Lo 2002 108
How is the keyboard divided?How is the keyboard divided?
n Typing arean Numeric keypadn Function keys
numeric keypad
typing area
function keys
28
© Peter Lo 2002 109
Portable KeyboardPortable Keyboard
n Full-sized keyboard you conveniently can attach and remove from a handheld computer
© Peter Lo 2002 110
Ergonomic KeyboardErgonomic Keyboard
n Designed to minimize strain on hands and wristsn Ergonomics incorporates comfort, efficiency, and
safety into design of items in workplace
© Peter Lo 2002 111
Alternative forms for commandsAlternative forms for commands
nMany programs allow you to use button, menu, or function key to obtain same result
Command Button Menu Function Key(s)
Copy Edit|Copy SHIFT+F2
Open File|Open CTRL+F12
Print File|Print CTRL+SHIFT+F12
© Peter Lo 2002 112
MouseMouse
n Pointing device that fits under palm of handn Controls movement of pointer, also called mouse
pointer, on screenn Pointer on screen takes several shapes
I-beam block arrow pointing hand
29
© Peter Lo 2002 113
How does mechanical mouse work?How does mechanical mouse work?n Rubber or metal ball is
on its undersiden Movement of mouse
translates into signals computer understands
mouse padmouse pad
ballball
wheel buttonwheel button
mousebuttonsmouse
buttons
© Peter Lo 2002 114
How does an optical mouse work?How does an optical mouse work?n Senses light to detect
mouse’s movementn More precise than
mechanical mousen Connect using a cable or
wireless
back buttonback
button
wheel buttonwheel button
forward button
forward button
optical sensor
optical sensor
© Peter Lo 2002 115
Common mouse operationsCommon mouse operations
n Pointn Clickn Right-clickn Double-clickn Dragn Right-dragn Rotate wheeln Press wheel
© Peter Lo 2002 116
TrackballTrackball
n Stationary pointing device with a ball on its topn To move pointer, rotate ball with thumb, fingers,
or palm of hand
trackball
30
© Peter Lo 2002 117
TouchpadTouchpad
n Small, flat, rectangular pointing device sensitive to pressure and motion
touchpad
© Peter Lo 2002 118
Pointing StickPointing Stick
n Pointing device shaped like pencil eraser positioned between keys on keyboard
pointing stick
© Peter Lo 2002 119
Joystick and WheelJoystick and Wheel
n Joystick is vertical lever mounted on a basen Wheel is steering-wheel type input devicen Pedal simulates car brakes and accelerator
joystick
pedal
wheel
© Peter Lo 2002 120
Light PenLight Pen
n Handheld input device that contains light source or can detect light
n Press light pen against screen surface and then press button on pen
light pen
31
© Peter Lo 2002 121
Touch ScreenTouch Screen
n Touch areas of screen with fingern Often used with kiosks
touch screen
© Peter Lo 2002 122
StylusStylus
n Looks like a ballpoint pen, but uses pressure to write text and draw lines
n Used with graphics tablets and handheld computers
stylus or pen
© Peter Lo 2002 123
Electronic SignatureElectronic Signature
n Pen and graphics tablet used with special software for handwriting recognition
n Legal as ink signature
n Also called e-signature
© Peter Lo 2002 124
Handwriting RecognitionHandwriting Recognition
n Translates handwritten letters and symbols into characters that the computer can understand
32
© Peter Lo 2002 125
How does voice recognition work? How does voice recognition work?
You’re right!
Step 1: Dictate
… Your write… You’re right… Your right
Natural Language Engine
your, you’re
right, writeMatches
Step 2: Convert analog to digital
Step 3: Check database for match
Step 4: Most likely match selected
© Peter Lo 2002 126
MIDI (Musical Instrument Digital MIDI (Musical Instrument Digital Interface)Interface)n External device, such as electronic piano keyboard,
to input music and sound effects
© Peter Lo 2002 127
How is a data entered into a How is a data entered into a handheld device?handheld device?
transfer data from desktop computer
digital camera
stylus
voice input
portable keyboard
stylus
handwriting recognition characters
stylus
on-screen keyboard
© Peter Lo 2002 128
Digital CameraDigital Camera
n Allows you to take digital pictures n Images viewable immediately on cameran Download to computern Post pictures to Web
33
© Peter Lo 2002 129
How does a digital camera work? How does a digital camera work?
7: View and manipulate image
2: Image focuses on CCD
3: CCD generates analog signal that represents image
1: Take picture
4: Analog signalconverts to digital signal
5: Digital signal processor (DSP) adjusts quality
Step 1Step 1
Step 2
Step 3
Step 1
Step 2
Step 4
Step 3
Step 1
Step 2
Step 5
Step 4
Step 3
Step 1
Step 2
Step 5
Step 4
Step 3
Step 1
Step 2
Step 6
Step 5
Step 4
Step 3
Step 1
Step 2
Step 7
6: Transfer image to computer
© Peter Lo 2002 130
ResolutionResolution
n Sharpness and clarity of imagen Higher the resolution, the better the image quality,
but the more expensive the cameran Pixel (picture element) is single point in electronic
imagen Greater the number of pixels, the better the image
quality
© Peter Lo 2002 131
Video InputVideo Input
n Process of entering full-motion recording into computer n Also called Video Capturen Video capture card is expansion card that converts analog
video signal into digital signalthat computer understands
n Video compression
analog video camera
analog video camera
digital video camera
digital video camera
© Peter Lo 2002 132
PC Video CameraPC Video Camera
n Digital video camera that allows home user to record, edit, and capture video and still images, and to make video telephone calls on Internet
n Also called PC Camera
PC video camera
34
© Peter Lo 2002 133
Web CamWeb Cam
n Video camera whose output displays on a Web pagen Also called a camn Streaming cam shows moving images by sending continual
stream of pictures
Web cam video output
© Peter Lo 2002 134
VideoconferencingVideoconferencing
n Two or more geographically separated people who use network on the Internet to transmit audio and video data
n Whiteboard is another window on screen that can display notes and drawings simultaneously on all participants’screens
© Peter Lo 2002 135
ScannerScanner
n Device that captures data directly from source documentuSource document is original form of data
OCR
flatbed scanner © Peter Lo 2002 136
How does a flatbed scanner work?How does a flatbed scanner work?
Step 1
Step 2
Step 1
Step 2
Step 3
Step 1
Step 2
Step 3
Step 4
Step 1
Step 2
Step 3
Step 4
Step 5
2: Bright light scans document
3: Image reflected into mirrors4: Light converted to analog electrical and then to digital signal
5: Digital information sent to computer
6: Print or save document
Step 6
1: Place document face down
Step 1
35
© Peter Lo 2002 137
Various types of scannersVarious types of scanners
Drum
Pen or handheld
Sheet-fed
Flatbed
© Peter Lo 2002 138
Image ProcessingImage Processing
n Capturing, storing, analyzing, displaying, printing, and manipulating imagesn Converting paper documents
into electronic formn Also called Imaging
© Peter Lo 2002 139
Optical ReaderOptical Reader
n Device that uses light source to read characters, marks, and codes and then converts them into digital datauOptical character recognition (OCR)uOptical mark recognition (OMR)uBar code scanner
© Peter Lo 2002 140
OCR FontOCR Font
n OCR font, such as OCR-A, used with OCR devicesn OCR device determines characters’shapes by
detecting patterns of light and darkn OCR software converts shapes into characters the
computer can understand
36
© Peter Lo 2002 141
Turnaround DocumentTurnaround Documentn You return it to
company that sent it
numbers are read by OCR device when document is returned
© Peter Lo 2002 142
Optical Mark Recognition (OMR)Optical Mark Recognition (OMR)
n Reads hand-drawn pencil marks, such as small circles or rectangles
© Peter Lo 2002 143
Bar Code ScannerBar Code Scanner
n Uses laser beams to read bar codes
bar code scanners
© Peter Lo 2002 144
Bar CodeBar Code
n Identification code that consists of a set of vertical lines and spaces of different widths
n Universal Product Code (UPC)
Number system character identifies type of product
Number system character identifies type of product
Manufacturer identification number
(Kellogg’s, in this case)
Manufacturer identification number
(Kellogg’s, in this case)
Check character verifies accuracy of scanned
UPC symbol
Check character verifies accuracy of scanned
UPC symbol
Item number (10 oz. box of Froot Loops
Item number (10 oz. box of Froot Loops
37
© Peter Lo 2002 145
Magnetic Ink Character Magnetic Ink Character Recognition Reader (MICR)Recognition Reader (MICR)n Can read text printed with magnetized inkn Banking industry almost exclusively uses MICR for check
processing
check number
bank number
check amount
account number
© Peter Lo 2002 146
Wireless InputWireless Input
n Handheld computer or device used to collect data wirelessly at the location where transaction or event takes place
n Data transferred later to desktop computer through docking station
© Peter Lo 2002 147
Input Devices for Physically Input Devices for Physically Challenged UsersChallenged Users
speech recognition
onscreen keyboard
pointing device for those with motor disabilities
keyguard for limited hand mobility
© Peter Lo 2002 148
New developments for physically New developments for physically challenged userschallenged usersn Gesture recognitionuComputer will detect human motionsuComputers with this capability have potential to
recognize sign language, read lips, track facial movements, or follow eye gazes
n ImplantationuFor paralyzed or speech- impaired individualsuDoctor will implant computerized device containing
transmitter into brainuAs user thinks, transmitter will send signals to
computer
38
© Peter Lo 2002 149
What Is output?What Is output?
video
audio
textgraphics
n Data that has been processed into a useful form, called information
© Peter Lo 2002 150
Output DeviceOutput Device
n Any hardware component that can convey information to a user
printer
monitor speakers
© Peter Lo 2002 151
Display DeviceDisplay Device
n Television-liken Information on a display device sometimes is
called Soft Copy
© Peter Lo 2002 152
CRT MonitorCRT Monitor
n Large sealed, glass screen
n Screen coated with tiny dots of phosphor material
n Pixel, or picture element, is single point in electronic image
n Three dots (red, blue, and green) combine to make up each pixel
CRT monitor screen
cathode ray tube
39
© Peter Lo 2002 153
Typical sizes for CRT monitorsTypical sizes for CRT monitors
n 15, 17, 19, 21, and 22 inch screen sizen Viewable size is
diagonal measurement of actual viewing area provided by the monitor
screen
size
viewab
le size
© Peter Lo 2002 154
Liquid Crystal Display (LCD)Liquid Crystal Display (LCD)
n Type of flat-panel displayn Uses liquid crystals between two sheets of
material to present information on screenn Electric current passes through crystals, which
creates images on the screen
© Peter Lo 2002 155
Some features of LCD screensSome features of LCD screens
n Lightweight and compactn Consumes less than one-
third of the power than does a CRT monitorn Ideal for notebook and
handheld computers
© Peter Lo 2002 156
WebWeb--enabled deviceenabled device
n Allows access to the Web or e-mailuCellular telephonesuPagers
nMany use monochrome LCD displays to save battery power
40
© Peter Lo 2002 157
Electronic Book (eElectronic Book (e--book) book)
n Small, book-sized computer that uses an LCD screenn Allows users to read, save, highlight, bookmark, and add
notes to online text
n Download new book contentfrom Web
© Peter Lo 2002 158
Two technologies used for LCD Two technologies used for LCD monitorsmonitorsn Active-matrix displayuCan display high-quality color viewable from
all anglesn Passive-matrix displayuColor often not as brightuImages best viewed when working directly in
front of display
© Peter Lo 2002 159
Gas Plasma MonitorGas Plasma Monitor
n Flat-panel display uses layer of gas plasma between two sheets of materialn Larger screen sizes and higher display quality than
LCD, but much more expensive
© Peter Lo 2002 160
Display resolutionDisplay resolution
n Describes the sharpness and clarity of imagen The higher the resolution, the sharper the image and the
more that can display on the monitor
800 x 600most common
1280 x 1024maximum resolution
of most monitors
800 horizontal pixels
600 vertical pixels
Total of 480,000 pixels on screen2048 x 1536
maximum for high-end monitors
41
© Peter Lo 2002 161
Dot PitchDot Pitch
nMeasure of the distance between pixels n Sometimes called Pixel Pitchn Smaller the distance between the pixels, the
sharper the imagen Use a monitor with a dot pitch of 0.29 millimeters
or lower to minimize eye fatigue
© Peter Lo 2002 162
Refresh RateRefresh Rate
n Speed at which monitor redraws images on the screenn Should be fast enough to maintain a constant,
flicker-free imagen High-quality monitor will provide refresh rate of
at least 75 hertzn Image on the screen redraws itself 75 times per
second
© Peter Lo 2002 163
Video CardVideo Card
n Converts digital output from computer into analog video signaln Controls how display device produces picturen Also called Graphics Cardor Video Adapter
© Peter Lo 2002 164
How does video travel from the How does video travel from the processor to a CRT monitor?processor to a CRT monitor?
Step 1Step 1Step 2
Step 1Step 2
Step 3
Step 1Step 2
Step 4
Step 3
Step 1Step 2
Step 3
Step 4
Step 5
Step 2
Step 3
Step 4
Step 5Step 6
Step 11: Processor sends digital data to video card
2: Video card converts digital data to analog signal3: Analog signal sent via cable to CRT monitor4: CRT separates signal into red, green, and blue signals
5: Electron guns fire color signals to front of CRT
6: Image displays
42
© Peter Lo 2002 165
Bit DepthBit Depth
24-bit video card
Uses 24 bits to store information about each pixel
Can display 16.7 million colors
224 = 16.7 million
colors
n Number of bits a video card uses to store information about each pixel
n Also called Color Depthn Determines number
of colors a video card can display
n Greater the numberof bits, better the resulting image
8-bit video card
Uses 8 bits to store information about
each pixel
Can display 256 different colors
28 =2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 =
256 colors
© Peter Lo 2002 166
What are video standardsWhat are video standards
n Video Electronics Standards Association (VESA) develops video standards
© Peter Lo 2002 167
What are various video card What are various video card configurations?configurations?
© Peter Lo 2002 168
Electromagnetic Radiation (EMR)Electromagnetic Radiation (EMR)
nMagnetic field that travels atspeed of lightn Small amount produced by all CRT monitors
Sit at arm’s length from
CRTEMR is greatest
on sides and back of CRT
monitor
LCD monitors do not pose
this risk
43
© Peter Lo 2002 169
ENERGY STARENERGY STAR®® ProgramProgram
n Program to encourage manufacturers to create energy-efficient devices that require little power when not in usenMonitors and devices meeting guidelines display
ENERGY STAR® label
© Peter Lo 2002 170
Interactive TVInteractive TV
n Two-way communications technology in which users interact with television programmingn HDTV works directly with interactive TV
Select a movie from
a central library of movies
Play games
Bank
ShopVote or respond to
network questionnaires
© Peter Lo 2002 171
PrinterPrinter
n Output device that produces text and graphics on papern Result is hard copy, or printout n Two orientations
portrait orientation
portrait orientation
landscape orientation
landscape orientation © Peter Lo 2002 172
Impact PrinterImpact Printer
n Forms characters by striking a mechanism against ink ribbon that physically contacts paper
n Ideal for printing multipart forms
n Can withstand dusty environments, vibrations, and extreme temperatures
44
© Peter Lo 2002 173
DotDot--matrix Printermatrix Printer
n Impact printer that produces printed images when tiny wire pins on print head mechanism strike inked ribbon
n Most use continuous-form paper
continuous-form paper
© Peter Lo 2002 174
How does dotHow does dot--matrix printer work?matrix printer work?
n When ribbon presses against paper, it creates dots that form characters and graphics
n A higher number of pins (9 to 24) means printer prints more dots per character, which results in higher print quality
dots form characters
© Peter Lo 2002 175
Line PrinterLine Printer
n High-speed impact printer that prints entire line at a time
n Speed measured by number of lines per minute (lpm) it can print
n Band printer prints fully-formed characters using a hammer mechanism
n Shuttle-matrix printer is high-speed printer that works more like a dot-matrix printer
© Peter Lo 2002 176
NonNon--impact printerimpact printer
n Forms characters and graphics on piece of paper without actually striking paper
ink-jet printerthermal printer
laser printer
45
© Peter Lo 2002 177
InkInk--jet Printerjet Printer
n Non-impact printer forms characters and graphics by spraying tiny drops of liquid ink onto piece of papernMost popular type of color printer for home use
© Peter Lo 2002 178
Resolution of a printerResolution of a printer
n Sharpness and clarity of charactersn Measured by number of dots per inch (dpi)
printer can output
300 dpi
1,200 dpi600 dpi
© Peter Lo 2002 179
How does an inkHow does an ink--jet printer work?jet printer work?
4: As vapor bubble collapses, fresh ink is drawn into firing chamber
firing chamber
ink dot
2: Vapor bubble forces ink through nozzle
nozzleink
1: Small resistor heats ink, causing ink to boil and form vapor bubble
bubble
resistor
Print cartridge
nozzleprint head
3: Ink drops onto paper
paper© Peter Lo 2002 180
Laser PrinterLaser Printer
n High-speed, high-quality non-impact printern Prints text and graphics in very high-quality resolution,
ranging from 600 to 1,200 dpi
n Typically costs more than ink-jet printer, but is much faster
46
© Peter Lo 2002 181
How does a laser printer work?How does a laser printer work?
drum
rotating mirror
drum
rotating mirror
drum
rotating mirror
drum
rollers
rotating mirror
drum
1: Drum rotates as paper is fed through2: Mirror deflects laser beam across surface of drum
3: Laser beam creates charge that causes toner to stick to drum4: As drum rotates, toner transfers from drum to paper5: Rollers use heat and pressure to fuse toner to paper
© Peter Lo 2002 182
Thermal PrinterThermal Printer
n Generates images by pushing electrically heated pins against heat-sensitive papern Ideal for small devices, such as adding machines
© Peter Lo 2002 183
Photo PrinterPhoto Printer
n Color printer that produces photo lab quality pictures and prints everyday documents
Select image to print, number of copies, and
size of print
© Peter Lo 2002 184
Label PrinterLabel Printer
n Small printer that prints on adhesive type material that can be placed on a variety of itemsnMost also print bar codes and e-stamps
47
© Peter Lo 2002 185
Portable PrinterPortable Printer
n Small, lightweight ink-jet or thermal printer that allows mobile user to print from notebook or handheld computer while traveling
© Peter Lo 2002 186
PlotterPlotter
n Sophisticated printer used to produce high-quality drawings
n Large-format printer similar to plotter and is used to print quality color prints
plotterlarge-format printer
© Peter Lo 2002 187
Audio Output DeviceAudio Output Device
n Computer component that produces music, speech, and other soundsn Speakers and headsets are common devices
woofer
speakers
© Peter Lo 2002 188
Voice OutputVoice Output
n Computer talks to you through speakers on computer RealPlayer
link to audio broadcast
48
© Peter Lo 2002 189
Internet TelephonyInternet Telephony
n Allows you to have a conversation over the Web, just as if you were talking on the telephone
© Peter Lo 2002 190
Data ProjectorData Projector
n Device that takes image from a computer screen and projects it onto a larger screen
data projector
© Peter Lo 2002 191
Facsimile (fax) MachineFacsimile (fax) Machine
n Device that transmits and receives documents over telephone lines
fax machine
© Peter Lo 2002 192
Fax ModemFax Modem
nModem that allows you to send and receive electronic documents as faxes
external fax modem
external fax modem
internal fax
modem card in system
unit
internal fax
modem card in system
unit
49
© Peter Lo 2002 193
Multifunction Device (MFD) Multifunction Device (MFD)
n Provides the functionality of a printer, scanner, copy machine, and fax machine
all in one
© Peter Lo 2002 194
TerminalTerminal
n Device that performs both input and output
special-purpose terminals
intelligent terminals
dumb terminals
© Peter Lo 2002 195
Dumb TerminalDumb Terminal
n Has a keyboard and monitor, but no processor or memoryn Connects to host
computer that performs processing and then sends output back
keyboard and monitor
© Peter Lo 2002 196
Intelligent TerminalIntelligent Terminalhost computer
intelligent terminal
n Has monitor, keyboard, memory and processor
n Similar to a PC in that it can perform tasks independent of host computer
n Programmable
50
© Peter Lo 2002 197
PointPoint--ofof--Sale (POS) terminalSale (POS) terminal
n Records purchases at point where purchase is made
n Output from POS terminals serves as input to hostcomputer
POS terminal in a grocery store
scanner and keyboard are input© Peter Lo 2002 198
Automated Teller Machine (ATM)Automated Teller Machine (ATM)
n Self-service banking machine that connects to host computer through telephone network
© Peter Lo 2002 199
What is the Magnifier command?What is the Magnifier command?
nWindows Magnifier command enlarges text and other items in window on screen
Location of mouse pointer magnified at top of screen
Location of mouse pointer magnified at top of screen
Magnifier command
Magnifier command
© Peter Lo 2002 200
Other output options for visually Other output options for visually impaired users?impaired users?n Change Window’s settings such as increasing size or
changing color of text to make words easier to readn Blind users can work with voice output
n Braille printer outputs information in Braille onto paper
Braille printer
51
© Peter Lo 2002 201
ReferencesReferences
n Computers in Your Future (Ch. 2)n Introduction to Computing (Ch. 3)n Discovering Computers World 2003 (Ch. 4 – 7)